Scientists have long known honeybees remove dead or diseased individuals from among their young, or "brood," to restrict the spread of pathogens through a colony. However, researchers wanted to better understand why some colonies are more ____________ about this cleanup than others are. Now a new study reveals some species, by releasing compounds to signal their death, use the smell of dead honeybees to help identify and breed healthier colonies. A. fastidious B. demanding C. susceptible D. diligent E. industrious F. vulnerable